Pituitary Histology Flashcards
Are there ducts in the endocrine system?
no
If vascularizaiton rich or poor in the endocrine system?
rich - so the hormones can get into the blood
The cells of the endocrine system are derived from what?
epithelium
What is necessary for a hormone to enact it’s function?
there needs to be the right receptor on the target cell
What are the endocrine glands that secrete amino acid-derivative hormones?
pituitary, thyroid, parathyroid, pancreatic islets
What germ layers do these glands develop from?
endocerm or ectoderm
What glands will secrete steroid hormones?
gonads and adrenal cortex
What germ layer do the gonads and adrenal cortex derive from?
mesoderm
What organelle will be particularly prominent in the glands that secrete steroids (the gonads and adrenal cortex)?
SER
How does the location of the target receptors differ between the amino acid hormones and steroid hormones?
amino acid hormones have receptors on the cell surface
steroids have receptor in the cytoplasm
What tissues of the enrocine system have discrete glands?
pituitary pineal thyroid parathyroids adrenals
What tissues of the endocrine system have both endocrine and exocrine function?
kidney, pancreas, gonads, placenta
What are the individual cells throughout the GI tract that are involved in the endocrine system?
DNES cells
What are the two parts of the pituitary?
adenohypophysis
neurohypophysis
How is the adenohypophysis derived?
from oral ectoderm
rathke’s pouch grows up from the roof ot he mouth to join the neurohypophysis
How is the neurohypophysis derived?
it’s neural ectoderm growing down off the diencephalon
What are the three parts of the adenohypophysis?
Pars tuberalis Pars distalis (makes up most of the pituitary gland) pars intermedia
What are the two parts of the neurohypophysis?
pars nervosa
infundibulum (neural stalk)
What system of blood vessels will deliver neurosecretory hormones from the primary capillary plexus of the median eminence to the secondary capillary plexus of the pars distalis?
the hypophyseal portal system of veins
Describe the parenchyma of the pars disatlis.
it’s anastomosin cords of cells with sinusoidal capillaries in between
some glassy-looking colloid
What are the two general cell types within the pars distalis. Exaplain the difference….
chromophobes (don’t take up stain)
Chromphils (take up stain) (about 50%)
note that the chromophobes are probably just chromophils that have lost their granules (about 50%)
What are the two types of chromophils? Which is more prevalent?
Acidophils (most prevalent)
basophils
What color do the acidophils stain?
red
What are the two kinds of acidophils?
somatotrophs
mammotrophs
What do the somatotrophs secrete?
growth hormone (or somatotropin)
What do the mammotrophs secrete?
prolactin
so increase in number during pregnancy and lactation
What are the three types of basophils?
thyrotrophs
gonadotrophs
corticotrophs
What do the thyrotrophs secrete?
thyroid stimulating hormone (TSH)
What do the gonadotrophs secrete?
Follicle stimulating hormone (FSH) and Lutenizing hormone (LH in females and interstitial stimulating homrone (ICSH) in males
In the gonadotrophs, are the FSH and LH stored in the same secretory vesicles or different ones?
same ones
What do corticotrophs secrete?
two things…
adrenocorticotropic hormone (ACTH)
Melanocyte-stimulating hormone (MSH)
True or false: the pars intermedia is well-developed in humans
false - it’s rudimentary
Are the pars intermedia cells weakly basophilic or acidophilic?
basophilic
What do they produce?
melanocyte-stimulating hormones (MSH)
There are cysts within the pars intermedia - what are they derived from?
they are remnant of Rathke’s pouch
follicles lined by cuboidal epithelium and filled with colloid
Why is the pars tuberalis such a highly vascularized area?
the superior hypophyseal arteries terminate here to form the primary plexus of portal veins
The cells of the pars tuberalis are basophilic and contain what hormones?
FSH and LH
What is the pars nervosa largely composed of?
about 100,000 secretory nerve cells
Are these secretory nerve cells myelinated?
no
Where are the cell bodies of these secretory nerve cells?
in the supraoptic and paraventricular nuclei of hypothalamus
What is this tract of nerves called?
the hypothalamic-hypophyseal stalk
THe pars nervosa has neurosecreotry vesicles synthesized in the cell bodies. What do they contain?
oxytocin or vasopressin
ATP
neurophysins
What are neurophysins?
specific binding proteins for oxytocin and vasopressin
Where do these neurosecretory vesicles accumulate?
herring bodies, which are dilated terminals adjacent to capillaries
What are the supportive cells found throughout the neural lobe (most similar to astrocytes)?
pituicytes
they are the nuclei that you can see in the pars nervosa
Which hypothalamic nuclei has cell bodies where most oxytocin is held?
the paraventricular
WHat will trigger secretion of oxytocin?
suckling (milk ejection reflex)
What does oxytocin cause?
contraction of the myoepthelial cells surorunding the alveoli and alveolar ducts of the mammary glands
also stimulates uterine smooth muscle contraction
What hypothalamic nucleus mainly has the vasopressin?
the supraoptic nucleus
What does vasopressin (ADH) do?
increases permeability of distal convoluted and collecting tubules to water to increase resorption and concentrate urine
What will stimualte ADH secretion?
increased plasma osmolality
decreased blood volume
